1. Field of the Invention
The present invention relates to a director chair, and more particular to a foldable chair comprising with outer frames, connecting units, seat supporting units and the back supporting units.
2. Description of the Related Art
The prior invention as shown in FIGS. 1 through 5, comprises two main leg frames, two interior leg frames and elastic plates. The main leg frames is in square shape and the interior leg frames is in  shape which are pivotally crisscrossed with each other with a suitable angle. Each elastic plate is positioned separately on top right angles of the interior leg frame pivotally connecting with the middle portion of each main leg frame. The lower portion of each interior leg frame is pivotally connected with the lower portion of the main leg frame. The canvas seat is installed between two interior leg frames. However, the prior invention mentioned above has the following shortcomings:
First, when unfolding the chair, top of the interior leg frames have to be held and pressed to elastically move the elastic plates downward in a flash moment which might clamp and hurt the user's fingers for the angles there between is getting smaller. Unless holding the top central portion of the interior leg frames and then pressing downward can prevent fingers from being hurt or even suffering bone fracture. However, it is still possible to hurt pats of the user's fingers during the unfolding process which might cause a huge safety concern.
Second, during folding process, in order to move the elastic plates downward, the bottom of main leg frames have to be stepped against to enforce the strength inwardly for folding the interior frames. When holding top of the interior leg frames, the back of the hands might be collided or clamped by the main leg frames resulting in difficulty for producing force and making folding process much more complicated and difficult.
Third, each connecting point of the elastic plate must be manufactured more accurate; otherwise, the function of others would be affected. However, the accuracy of the manufacture would relatively lower the producing effectiveness and market competitiveness.
Fourth, the whole structure would easily be damaged and deformed, once the elastic plates suffer from the user's weight for a long time.
Fifth, the length of the seat installed between the main and interior leg frame would be limited and the user's legs would easily bump into the front edge of the interior leg frame which is positioned within the main leg frame.
As shown in FIGS. 6 and 7, in order to improve the prior art mentioned above, the applicant has filed by Ser. No. 12/218,273 in US patent. A foldable director's chair comprises armrest units, leg frame units, gliding tubes, seat supporting units, back supporting units and connecting units. The armrest unit and a leg frame unit which are both hollow tubes with their right angle ends extending downward or upward for a suitable length against each other and connected through by a gliding tube. The retaining sleeves connect the armrest and leg frame unit so that one end of each gliding tube can be engaged through the armrest tube and fixed to each other via the retaining sleeves while another end engaged through the leg frame unit without being fixed allowing the armrest unit moving straightly upward or downward along the gliding tube. Inside edge of each retaining sleeve, there is a protrusion extending there from and pivotally engaged with each end of arc-shaped connecting unit respectively. The back supporting units need to be pressed down by hand to the armrest units when being in a folding position.